TiAlB coatings with different compositions were deposited by co sputtering from TiAl and TiB2 targets onto AISI316 stainless steel substrates at a temperature of 170 C. The stoichiometry and nanostructure have been studied by xray photoelectron spectroscopy (XPS), xray diffraction (XRD) and transmission electron microscopy (TEM). Analysis of the XPS spectra suggests the presence of phases in agreement with the equilibrium TiAlB phase diagram. Diffraction studies (XRD and TEM) indicate that coatings with B/Al ratios 6 are amorphous, while coatings with B/Al ratios 6 exhibit a nanocomposite structure with average TiB2 grain sizes of 2-3 nm for the highest B/Al ratio of 16. Nanocomposite coatings show significantly improved H/E ratios which is beneficial when protecting soft steels and light alloys. .